A large demand is expected for polyamide resins as engineering plastics due to their superior material properties. However, their impact strength, especially low temperature shock resistance is not quite satisfactory and improvement thereof has long been expected. As a measure for improving the shock resistance, it is described, for example, in Japanese Patent Kokais Sho 55-9661 A and Sho 55-9662 A, that the Izod impact strength of polyamide resin is improved by blending an ethylene/.alpha.-olefin copolymer obtained by grafting an .alpha., .beta.-unsaturated carboxylic acid onto a polyamide resin. However, such a technical measure of improving the Izod impact strength by mixing with an ethylene/.alpha.-olefin copolymer brings about a new problem that the rigidity of the resulting polyamide resin is thereby decreased considerably. In addition, the resulting resin will exhibit insufficient falling-weight impact strength at low temperatures, so that the low temperature impact strength of practical molded articles is not satisfactory.
In Japanese Patent Kokai Sho 59-78256 A, a polyamide resin composition is disclosed, which contains a polyamide, a modified ethylene/.alpha.-olefin copolymer and an ethylene homopolymer and exhibits an improved shock resistance. This polyamide resin composition brings about, however, only an insufficient improvement in the low temperature shock resistance, since the ethylene homopolymer incorporated here has a large molecular weight distribution value (Mw/Mn).